You can't do multiple fields separated by commas. If you want to build the address, you need to do it something like this (I'm also adding carriage returns so it appears on multiple lines and testing for null values in addr2.)
if CurrentDate = {AR14.DATE_CREATED} then
if IsNull(AR14.CUST_ADDR2) then
{AR14.CUST_NAME} + chr(10) + chr(13) + {AR14.CUST_ADDR1} + chr(10) + chr(13) +
{AR14.CUST_CITY} + ', ' +{AR14.CUST_STATE} + ' ' +{AR14.CUST_ZIP}
else
{AR14.CUST_NAME} + chr(10) + chr(13) + {AR14.CUST_ADDR1} + chr(10) + chr(13) +
{AR14.CUST_ADDR2}+ chr(10) + chr(13) + {AR14.CUST_CITY} + ', ' +{AR14.CUST_STATE} + ' ' +{AR14.CUST_ZIP}
else Next (AR.14.INV_NUMBER)